PatchTheCVECVE-2025-66567: The ruby-saml library is for implementing the client side of a SAML authorization
CVE-2025-66567 is a critical-severity flaw (CVSS 9.1) affecting ruby-saml. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
The ruby-saml library is for implementing the client side of a SAML authorization. ruby-saml versions up to and including 1.12.4 contain an authentication bypass vulnerability due to an incomplete fix for CVE-2025-25292. ReXML and Nokogiri parse XML differently, generating entirely different document structures from the same input. This allows an attacker to execute a Signature Wrapping attack. This issue is fixed in version 1.18.0.
Why this priority
- Critical severity
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.1 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.4% (top 64%) |
| CISA exploited list | No |
| Weakness | CWE-347 |
| Published | 2025-12-09 |
| Last modified | 2026-10-14 |
Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2025-66567?
ruby-saml: upgrade to 1.18.0. Exact commands for each OS are on this page.
Is CVE-2025-66567 being exploited?
CVE-2025-66567 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2025-66567 affect?
CVE-2025-66567 affects ruby-saml. Severity is critical (CVSS 9.1). The ruby-saml library is for implementing the client side of a SAML authorization. ruby-saml versions up to and including 1.12.4 contain an authentication bypass vulnerability due to an incomplete fix for CVE-2025-25292. ReXML and Nokogiri
How urgent is CVE-2025-66567?
Priority 46/100. Critical severity; Remotely exploitable, no login, no user action
Software pages
Related CVEs
- CVE-2025-66568 CRITICAL 9.1 UPGRADE The ruby-saml library implements the client side of an SAML authorization
- CVE-2025-25293 HIGH 7.5 UPGRADE UPGRADE ruby-saml provides security assertion markup language (SAML) single sign-on (SSO) for Ruby
- CVE-2025-25292 CRITICAL 9.8 UPGRADE UPGRADE ruby-saml provides security assertion markup language (SAML) single sign-on (SSO) for Ruby
- CVE-2025-25291 CRITICAL 9.8 UPGRADE UPGRADE ruby-saml provides security assertion markup language (SAML) single sign-on (SSO) for Ruby
- CVE-2024-45409 CRITICAL 10.0 UPGRADE UPGRADE The Ruby SAML library is for implementing the client side of a SAML authorization